Scary Lockup

[Guest robbie]

Finally (I hope) got over all engine probs only to be really scared when I hit the brakes and find the fron wheels lock instantly leaving no control

I have fitted the brake bias thingy at same angle as was on sierra and having read some previuos posts I see that this may simply need adjustment.

However, is it possible to lose the bias and rely on equal pressures to give balanced braking?

Whatcha think?

 

Regards

 

Robbie

[Guest carl leonard]

If I were you I would remove the bias value altogether. I have not fitted one and the car passed the SVA with no problems. The tester even remarked how good the brakes were!

 

Make sure you have fitted new brake shoes / pads / discs all round as this helps quite alot (Ask Dave Wilson !!!)

 

Carl.

[Peter Bell]

The brake inertia thingy stops the rear brakes from locking up before the fronts so if the fronts are locking then it will not prevent that, if you can't tread lighter on the pedal you could try disconnecting the servo vacuum pipe.

Peter

[Guest timswait]

What type of brakes do you have on the back? If you have drums (even the larger size drums) the general consensus seems to be that the Sierra's valve is unneccesary, and probably does more harm than good. I have the large drums fitted and passed SVA and the car always locks the front wheels first (this is the right way, the rear wheels should NEVER lock before the front) without the valve. If you have discs on the back you may need the valve, I'm not sure. If you want to test the effects of removing the valve with less effort then mount it vertically, in this position it will do nothing.

[Guest salty_monk]

Pretty sure I don't have the valve either, what does it look like & where would it be fitted?

 

Fronts always seem to lock first on mine too (Drums, axle from a 2.0 EFI)

[Guest timswait]

The valve is a barrel shaped thing, about 4 inches long and two or three in diameter. It will be in the rear brake line between the master cylinder and the rear wheels, on the Sierra it would be mounted inside the engine bag on the inside of the wheel arch (as I remember), could be mounted anywhere on a Hood. The front wheels should always lock before the rear under any loading or road conditions. There's a section in the SVA test to ensure this is the case, and most of the time hoods pass it easily without the valve.

[Peter Bell]

Salty, this is on the main site and shows how the pressure reducer thng works, sorry haven't sorted out the link thing.

http://www.rhocar.org/content.php?article.17

Peter

[Guest robbie]

I have drums on the back and discs on front and appreciate the front should lock before back but the balance feels like 90% front! A doctor would pronounce it as a chronic condition of front wheel lock!!!

I think it is nessessary to perform bypass surgery and remove offending body (valve).

Anyone who reckons otherwise please speak now or the hood goes under the knife this weekend.

I will keep you informed of her post op condition

 

Thanks

 

Robbie (MD)

[Guest salty_monk]

Nope definitely don't have one of these... Have to admit the brakes are very light (don't need much pressure) especially compared to our Moggy no servo all drums but they work well enough...

You're probably just not used to it, be light with, don't stamp on it & you'll get some feel for it. Doesn't look like you'll do any harm with taking the valve out though, perhaps you have it at the wrong angle??

[Guest Ianz]

All

 

The simple fact is that a Robin Hood using Sierra components is

overbraked!!!!, because their is'nt the weight ,having now done a few

miles in mine I now make sure I brake early and gently, otherwise

my front wheels lock up.

 

IMHO

 

Cheers Ian

[Guest paul thompson]

I have the brake refurbishment kit from RHE which is non vented solid discs (which seem to me marginally smaller than the Sierra's) and Calipers from an Escort. I have a PCRV valve in line (not the sierra valve, they're crap for a hood) and the large drums on the back. I find brake performance very good, the front only locks up when you give it a good hoofing on the brake pedal. Otherwise very happy. I still have the brake booster connected and during SVA they test the brakes with and without, i.e. with engine runing and with engine off. There was not a lot of difference. You could try disconnecting the booster BUT remember to block it off otherwise the manifold will suck in loads of air and cock up the carb/injection system.